Diameter dependence of ferromagnetic spin moment in Au nanocrystals

TL;DR

This paper investigates how the ferromagnetic spin moment in gold nanocrystals varies with particle diameter, revealing a maximum at about 3 nm and discussing a possible size-dependent spin correlation mechanism.

Contribution

It demonstrates the diameter dependence of ferromagnetism in Au nanoparticles and proposes the Fermi hole effect as a potential explanation for the observed size-dependent magnetization.

Findings

Maximum magnetic moment at ~3 nm diameter

Diameter dependence of ferromagnetism in Au nanoparticles

Proposed Fermi hole effect as a mechanism

Abstract

Au nanoparticles exhibit ferromagnetic spin polarization and show diameter dependence in magnetization. The magnetic moment per Au atom in the particle attains its maximum value at a diameter of about 3 nanometer (nm) in the Magnetization-Diameter curve. Because Au metal is a typical diamagnetic material, its ferromagnetic polarization mechanism is thought to be quite different from the ferromagnetism observed in transition metals. The size effect strongly suggests the existence of some spin correlation effect at the nanoscale. The so-called ``Fermi hole effect'' is the most probable one given in the free electron gas system. Ferromagnetism in Au nanoparticles is discussed using this model.